32 PROCEEDINGS OF THE 



and nearly their own diameter apart. The keel of the interstices 

 bears a single row of closely-set tnbercnles, as numerous as the cell 

 apertures. Dissepiments thin, slightly keeled, half the thickness of 

 the interstices, and crossing them at nearly right angles, excepting 

 at those portions of the frond where the interstices become much 

 branched ; they then cross obliquely, giving an angulated form to the 

 fenestrules in those parts. Cells round, with a slightly raised lip 

 on their lower or outer margin, about their own diameter apart, 

 four to five in number on each side of the length of a fenestrule, 

 twenty to twenty-five in five fenestrules. Cells confined to the 

 interstices, excepting at those portions of the frond where the inter- 

 stices become much branched, and they there encroach on the 

 dissepiments. 



Supplementary cells of the same size also occur irregularly amongst 

 the fenestrules, and are placed on a lower level of the interstice than 

 the former, where they alternate with the other cells. These sup- 

 plementary cells are very irregular in number, some fenestrules show 

 none, others shoAv from one to four, while on other interstices or 

 stems, they are so regular as to show a double row of cells on each 

 side of the keel, somewhat like that of the Permian Synodadia. 

 Where these supplementary cells occur in ones and twos, they are 

 seen to project inwards upon the open space of the fenestrules with 

 crater-like mouths extending beyond the level of the upper row, and 

 thus giving the celluliferous face a somewhat rough and ragged 

 appearance in unworn specimens. Small secondary pores or fora- 

 mina occur scattered somewhat irregularly amongst the larger cells, 

 and are about four times less in diameter. One is to be seen gener- 

 ally between each of the larger cells, sometimes two, the one being 

 placed above or alongside the other ; while between other cells often 

 none of the small pores are to be observed. 



Reverse, or non-celluliferous face. Fenestndes oblong, oval in 

 form, caused by the junction of the expanded ends of the dissepiments 

 with that of the interstices. Surface ornamented by numerous 

 closely-set granular tubercules. The worn surface shows longitudinal 

 striation of the interstices. Small pores or foramina. These are 

 of the same size and character as those seen on the celluliferous 

 face, and are scattered about in no regular order, although they seem 

 to be rather more abundant on the lower portion of the fronds than 

 on the upper. 



The form under description is readily distinguished from the other 



